If I remember well, it was Uncharted 1.
Most difficult was GOD OF WAR III. Oh my F'n god.....What a nightmare. But felt sooo good.
Keep on Gaming.

Not really. Not all games reqiure it. For instatce, Uncharted 2 you could get the platinum with the disk based game because the DLC was released at a later date. So you could now had the trophy but not be 100% on that game. 

So games have multi-player spacefic trophies, and some dont.  I hated Resistance 2 for that. Get 10,000 multi-player kills. REALLY ??. whatever man.

I have platinum for Bad Company 2 and Walking Dead, 100% on Contrast, Xmen, and Worms. I don't pay attention to trophies unless I really like the game like Bad Company 2. I am liking AC4 so much I am going to go for that one on PS4.

The First Platinum Trophy was:

Final Fantasty XIII

I felt kind of cheated after beating the game and since I had the strategy guide (which I use until after I beat the game) it felt necessary. Was a bad trophy to get, but my second one (Skyrim) was even worse, as I did it before the big patch and literally had to reboot my PS3 8 times due to lockups during the 1000 in bounty from all major holds trophy (last one I needed for the plat).

Uncharted 2 was my first and only platinum. After that I realized I never wanted to try to get another. What a waste of time. I play games to have fun. Getting a trophy for doing something that is boring, is not my definition of fun.

First one was Assassin's Creed 2, got it a month ago.